KR101188054B1 - STEEL PIPE WITH A FUNCTION OF CONVEYING 400bar HIGH-PRESSURE CONCRETE AND THE METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

Disclosed is a concrete high pressure press tube improved by 850 MPa tensile strength, 270 Hv hardness, 400 bar pressure resistance performance, and a manufacturing method thereof.
The method for producing a concrete high pressure pump according to the present invention, in weight%, carbon (C): 0.27 to 0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03 % Or less, boron (B): 0.004% or less, Slitting step of slitting the heat-treated steel composed of the remaining iron (Fe) and other unavoidable impurities to the outer diameter width of the pressure vessel to form a skelp ; Leveling and edge milling steps to adjust flatness and polish edges while releasing the roll-shaped skelp; A roll forming step of forming the skelp through the leveling and edge milling into a multi-stage roll to form a pipe; A pressure pipe tube tube step of welding the pressure pipes by welding both edges of the skelp after the roll forming; And a pressurized tube heat treatment step of heat-treating the assembled pressurized tube into a tempered martensite structure to be suitable for conveying concrete at 400 bar pressure.

Description

Method for manufacturing concrete high pressure pressurized pipe with improved 850 MPa tensile strength, 270HH hardness and 400ｂa pressure resistance performance {STEEL PIPE WITH A FUNCTION OF CONVEYING 400bar HIGH-PRESSURE CONCRETE AND THE METHOD OF MANUFACTURING THE SAME}

The present invention relates to a high pressure concrete pipe and improved manufacturing method of 850MPa tensile strength, 270Hv hardness, 400bar pressure resistance performance, concrete, which can improve the pressure resistance and wear resistance to pressurize the concrete at a high pressure of 400bar when building a high-rise building It is a technique regarding a high pressure pressure pipe and its manufacturing method.

Concrete pressurized pipe means a pipe member which carries concrete using pressure.

Concrete is a material with a higher specific gravity than water, so in order to effectively transport it to the upper level, it is necessary to secure mechanical properties of the steel pipe itself, which can endure very high pressure.

At present, there is an increasing interest in the construction of high-rise buildings, and according to this trend, there is an urgent need for a pressure pipe with improved pressure resistance and wear resistance that can effectively transport concrete to the height of a high-rise building.

To date, pressure pipes manufactured by heat-treating general structural steels (eg STK490) and heat-treated steel sheets (eg, S45C) have been on the market, but are superior to the conventional pressure pipes. There is an urgent need for the development of a pressure pipe that can have a pressure resistance characteristic.

An object of the present invention is to provide a high-pressure concrete pipe, which can pressurize concrete at a pressure of 400 bar by securing mechanical properties of tensile strength (TS) 850 MPa and hardness 270 Hv as the heat treated steel is effectively heat treated.

Another object of the present invention is to properly present the composition ratio of the heat treatment steel grade necessary for manufacturing the above-mentioned concrete high pressure feed pipe, and to propose the appropriate heat treatment conditions so as to achieve the desired pressure resistance performance, suitable for the construction of high-rise buildings. The present invention provides a method for producing a concrete pressure pipe.

The problem to be solved by the present invention is not limited to the above-mentioned problem, another task that is not mentioned will be clearly understood by those skilled in the art from the following description.

According to the spirit of the present invention, (a) wt%, carbon (C): 0.27 ~ 0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less , Boron (B): less than 0.004%, the slitting step of slitting the heat-treated steel composed of the remaining iron (Fe) and other unavoidable impurities to the outer diameter width of the pressure vessel to form a skelp; (b) leveling and edge milling steps to adjust flatness and polish edges while releasing the rolled skelp; (c) a roll forming step of forming the skelp through the leveling and edge milling into a multi-stage roll to form a pipe; (d) a pressure pipe tube tube step of welding the pipes by welding both edges of the skelp after the roll forming; (e) a pressure pipe heat treatment step of heat-treating the pipe tube to the tempered martensite structure to be suitable for conveying the concrete at a pressure of 400 bar provides a high pressure concrete pipe manufacturing method comprising a.

Further, according to another idea of the present invention, in weight%, carbon (C): 0.27 to 0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03 % Or less, boron (B): 0.004% or less, and heat-treated steel composed of the remaining iron (Fe) and other unavoidable impurities slitting to the outer diameter width of the pressure pipe to form a skelp, The pressure pipes constructed using the concrete provide a high pressure concrete pipe which is heat-treated with tempered martensite tissue to be suitable for pumping concrete at a pressure of 400 bar.

According to the concrete high pressure pressure pipe of the present invention and a method of manufacturing the same, by using a heat treatment steel grade, by effectively quenching and tempering (tempering) heat treatment, such as better tensile strength (TS) and hardness (Hv) Since mechanical properties can be secured, there is an advantageous effect of providing a concrete high pressure pressure pipe required for the construction of a high-rise building.

In addition, according to the concrete high pressure pump and the manufacturing method of the present invention, in order to manufacture the above-mentioned concrete high pressure pump, it is possible to correctly present the composition ratio of the heat treatment steel species required, and to achieve the desired pressure resistance performance, The competitiveness can be improved.

1 is a flow chart showing a concrete high pressure pressure pipe manufacturing method according to an embodiment of the present invention,
2 is a structure photograph shown to explain the change in the structure before and after the heat treatment in the concrete high pressure pressure pipe according to an embodiment of the present invention,
Figure 3 is a tissue picture of Comparative Example 1 shown for comparison with an embodiment of the present invention.

Hereinafter, a description will be given of a preferred embodiment of a concrete high pressure pressure pipe according to the present invention and a manufacturing method thereof.

Advantages and features of the present invention, and methods of achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

Hereinafter, with reference to the accompanying drawings it will be described in detail with respect to the concrete high-pressure pump and the manufacturing method according to a preferred embodiment of the present invention.

Improved concrete high pressure pump with 400bar pressure resistance

Concrete high pressure pressure pipe according to the present invention is to pipe the pressure pipe using a heat-treated steel grade of carbon content of 0.27 ~ 0.29% by weight so that the pressure resistance and wear resistance required for the concrete can be improved during construction of a high-rise building.

As the heat-treated tube is heat-treated by the manufacturing method according to the embodiment of the present invention, the tensile strength (TS) is 850MPa or more, the hardness is to ensure the mechanical properties of 270Hv or more.

As a result, the concrete high pressure pressure pipe according to the present invention may have a pressure resistance characteristic of 400 bar.

Concrete high pressure pressure tube according to the present invention, in weight percent, carbon (C): 0.27 ~ 0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less , Boron (B): 0.004%, the remainder is prepared using a heat-treated steel composed of iron (Fe) and other unavoidable impurities.

Referring to the role and the content of each component included in the concrete high pressure pump according to the present invention as follows.

Carbon (C): 0.27-0.29 wt%

Carbon is an important element that allows martensite transformation to occur after heat treatment in subsequent processes, and serves to enhance the strength of the steel. In other words, austenite solid solution forms martensite structure during quenching heat treatment.

Such carbon may help to improve the martensite fraction as the content thereof increases, and it is preferable to add 0.27 to 0.29% by weight based on the total weight of the concrete high pressure pump according to the present invention. More preferably 0.28% by weight.

If the carbon content is less than 0.27% by weight, it is difficult to secure sufficient strength. If the carbon content is more than 0.29% by weight, it may adversely affect workability, and the weldability and toughness may be deteriorated.

Manganese (Mn): 1.80 wt% or less

Manganese is an effective element that raises the strength without lowering the toughness.

In particular, as a solid solution strengthening element, it improves the hardenability of steel and contributes to improving the yield strength and tensile strength of carbon steel.

In addition, manganese increases the depth of cure during the quenching heat treatment, but if excessively large amounts are contained, quenching cracks or deformation may be caused.

Therefore, in the case of the concrete high pressure pump according to the present invention, the content of manganese is preferably limited to 1.80% by weight. As a preferred embodiment, 1.80% by weight can be presented.

Boron (B): 0.004 wt% or less

Boron is an element that significantly increases the hardenability by only a small amount of addition, but when excessively added, Fe ₃ B forms and causes red brittleness. Therefore, it is preferable to add the limited to 0.004% by weight or less with respect to the total weight of the concrete high pressure pump according to the invention.

Phosphorus (P): 0.03 wt% or less

Phosphorus is an impurity element present in steel and is an advantageous element for improving strength and corrosion resistance. However, excessive addition may significantly impair the impact toughness, so it is desirable to keep the content as low as possible.

The phosphorus content is added to the total weight of the concrete high pressure pressure pipe according to the present invention is limited to 0.03% by weight or less.

Sulfur (S): 0.03 wt% or less

Sulfur, like phosphorus, is an impurity element present in steel.

In particular, since such sulfur forms an emulsion-based inclusions such as MnS, which can greatly inhibit the toughness and strength of the steel, it is advantageous to keep the content as low as possible.

Therefore, the content of sulfur is preferably limited to 0.03% by weight or less based on the total weight of the concrete high pressure pump according to the present invention.

The prepared heat-treated steel is slitting to the outer diameter width of the pressure feed pipe, and formed into a skelp.

Such a skelp can be manufactured into a concrete high pressure pressure pipe required for the construction of a high-rise building through the pipe work.

In the high pressure concrete tube according to a preferred embodiment of the present invention, the targeted pressure resistance is 400 bar, and should correspond to a tensile strength (TS) of about 850 MPa and a hardness standard of about 270 Hv.

1 is a flowchart illustrating a method of manufacturing a concrete high pressure pressure pipe according to an embodiment of the present invention.

Hereinafter, with reference to Figure 1, it will be described in detail with respect to the manufacturing method of the concrete high pressure pump according to a preferred embodiment of the present invention.

First, in weight percent, carbon (C): 0.27 to 0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less, boron (B): 0.004% Hereinafter, a heat treatment steel composed of the remaining iron (Fe) and other unavoidable impurities is slitting to the width of the outer diameter of the pressure feed pipe to form a skelp (S100).

Next, leveling and edge milling to adjust the flatness and polish the edge while releasing the roll-shaped skelp are performed (S200).

When the leveling and edge milling is completed, the roll forming is performed to form a skelp into a multi-stage roll to form a pipe shape (S300).

Next, the pressure pipe is manufactured by welding both edges of the skelp after the roll forming (S400). At this time, preferably, electric resistance welding may be used as a welding method used for edge welding of both ends of the skelp.

Between the pressure tube manufacturing step (S400) and the pressure tube heat treatment step (S500) to be described later, more preferably, during the pipe work of the pressure tube, it may include the step of removing the beads formed on the weld surface.

The corrugated push tube is then heat-treated with tempered martensite tissue, suitable for pushing concrete at 400 bar pressure (S500).

At this time, the heat treatment step (S500) is a step of transforming the tempered martensite structure in order to improve the strength and pressure resistance performance of the pressure vessel was a ferrite + pearlite structure before heat treatment.

First, the prepared pressure feed tube is subjected to normalizing which heats up to the austenite transformation point. Next, a quenching step (S520) of quenching the heated feed tube is performed. Subsequently, a tempering step S540 of re-heating the quenched pressure feed pipe and performing slow cooling is performed.

Here, normalization of the pressure feed pipe is performed in order to refine the welded structure of the pressure feed pipe that is formed through electrical resistance welding and to homogenize the internal and external textures of the pressure feed pipe.

In particular, through this normalization, the pressure vessel is heated to a uniform austenite structure to ensure a standardized structure. To this end, it may be heated to 900 ~ 1000 ℃ preferably a stable solid solution temperature of austenite.

Next, the quenching heat treatment step (S520) is performed. Quenching is one of heat treatment methods for steel, and refers to a heat treatment method for steel commonly referred to as quenching as a method of quenching a steel material heated at high temperature.

The quenching heat treatment in this step is to quench the pressure pipe heated to 900 ~ 1000 ℃, preferably the heated pressure feed through the water pressure of the cooling water (for example, water) is injected at a high pressure of 2.9 ~ 3.1 kg / ㎠ Cool the tube quickly.

By the quenching heat treatment, the pressure pipe is improved in hardness, but the brittleness appears, so that the tempering heat treatment step (S540) to remove the internal stress in accordance with the purpose of use of the concrete high pressure pressure pipe.

In the tempering heat treatment step (S540), the pressure pipe after the quenching heat treatment is reheated and then cooled slowly.

And here, although the temperature at the time of tempering is preferable that it is 520-540 degreeC, it improves the low-temperature impact toughness of a pressure feed pipe, and suppresses a hardness variation.

And through this tempering heat treatment, the pressure pipe is reinforced from the ferrite + pearlite structure to the tempered martensite structure before the heat treatment, it can be improved pressure resistance and wear resistance.

And, more preferably, it may further comprise the step of performing a straightness and diameter size correction for the pressure-reducing pipe generated during the heat treatment.

The equipment required to perform the straightness and diameter size calibration for the pressure pipe is a tube pipe straightener, which is not significantly different from the equipment used in general, detailed description of the equipment will be omitted.

Through all the above-mentioned steps, the concrete high pressure pressure pipe according to the preferred embodiment of the present invention can withstand the internal pressure of 400 bar, it is possible to meet the target tensile strength 850MPa and hardness 270Hv standards.

These results will be described in detail through the following examples.

Example

Concrete high pressure pump according to the present invention, through the above-described manufacturing method, while ensuring a tensile strength of 850MPa, while ensuring a minimum hardness of 270Hv, it is manufactured to be suitable for conveying concrete at a pressure of 400bar .

Hereinafter, preferred embodiments of the present invention will be described in comparison with Comparative Examples 1, 2, and 3 through the following [Table 1].

[Table 1]

This embodiment uses a carbon-treated heat-treated steel sheet having a carbon content of 0.28% by weight, and in Comparative Examples 1 and 3, a non-heat treated steel grade is used as an STK 490-like steel grade, and in Comparative Example 2, a high-carbon heat treated steel grade is an S45C-like steel grade. It is used.

Each product specification has a similar shape to each other in diameter and thickness as disclosed.

Figure 2 is a tissue photograph showing a comparison of the structure before and after the heat treatment of this embodiment.

In the case of Figure 2 (a), as can be confirmed through the tissue picture, the ferrite, pearlite structure is confirmed.

And when the quenching and tempering heat treatment according to the present invention of Figure 2 (a), as can be seen in Figure 2 (b) it can be seen that transformed into a tempered martensite (tempered martensite) tissue.

On the other hand, the following [Table 2] shows the mechanical properties of the Examples and Comparative Example 1 compared to the composition in the above [Table 1].

[Table 2]

And, the tissue picture of the Example and Comparative Example 1 according to the present invention can be confirmed through Figure 3, Figure 3 (a) is a tissue picture of the pressure-conducting tube manufactured according to the present invention, Figure 3 (b ) Is a structure photograph of Comparative Example 1 of [Table 1] and [Table 4].

As can be seen through the Figure 3, the structure between the Example and Comparative Example 1 is different, in particular, in the case of the embodiment of the present invention of Figure 3 (a), it is confirmed that formed of tempered martensite (tempered martensite) tissue Can be.

By such a tempered martensite structure, the tensile strength of the pressure vessel according to the present invention was 850Mpa, the hardness was sharply increased to 270Hv, it was confirmed that secured significantly improved mechanical properties compared to Comparative Example 1.

On the other hand, using the embodiment of the present invention, as a result of performing a hydraulic test, it was possible to obtain a result that the present invention is suitable for conveying concrete at a pressure of 400 bar as the target.

In summary, the high-pressure concrete pipe of the present invention is a high-pressure non-heat treated steel grade (e.g. STK 490) or a high-carbon heat-treated steel grade (e.g. S45C) in place of the heavy carbon steel heat treated steel (e.g., carbon weight% 0.27 ~ 0.29) I use it.

Then, quenching and tempering heat treatment are performed under appropriate conditions.

As a result, it was possible to secure a tensile strength (TS) of 850 Mpa and a hardness of 270 Hv, and have a pressure resistance and abrasion resistance suitable for high pressure concrete pressure feeding of 400 bar.

So far, concrete embodiments of the high pressure concrete pressure pipe of the present invention and a method of manufacturing the same have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

In other words, the foregoing embodiments are to be understood in all respects as illustrative and not restrictive, the scope of the invention being indicated by the following claims rather than the foregoing description, and the meanings of the claims and All changes or modifications derived from the scope and the equivalent concept should be construed as being included in the scope of the present invention.

S100: Slitting Step
S200: Leveling and Edge Milling Steps
S300: Roll Forming Step
S400: pressure pipe tube step
S500: heat treatment step
S520: quenching step
S540: Tempering Step

Claims (5)

(a) In weight%, carbon (C): 0.27-0.29%, manganese (Mn): 1.80% or less, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less, boron (B): 0.004 A slitting step of slitting a heat-treated steel composed of% or less, remaining iron (Fe) and other unavoidable impurities to an outer diameter width of a pressure pipe to form a skelp;
(b) leveling and edge milling steps to adjust flatness and polish edges while releasing the rolled skelp;
(c) a roll forming step of forming the skelp through the leveling and edge milling into a multi-stage roll to form a pipe;
(d) a pressure pipe tube tube step of welding the pipes by welding both edges of the skelp after the roll forming;
(e) a pressure tube heat treatment step of heat-treating the corrugated pressure tube with tempered martensite tissue to be suitable for conveying the concrete at 400 bar pressure;
In step (e),
(e-1) a normalizing step of heating the pressure feeding tube formed in step (d) to an austenite transformation point;
(e-2) quenching to quench the heated pressure feed tube; And
(e-3) a tempering step of slow cooling after reheating the quenched pressure feed pipe;
In the step (e-2), the quenching of the pressure pipe is carried out by a water cooling method by water of 2.9 ~ 3.1 kg / ㎠ pressure,
In the step (e-3), the tempering of the pressure pipe is heat-treated at a rate of 5 m / min at a temperature of 520 ~ 540 ℃, and then the method of manufacturing a concrete high pressure pressure pipe, characterized in that the air cooled to room temperature . delete delete delete delete

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